Variable depth moored sweep

ABSTRACT

This apparatus, described in the following specification, comprises an improved system for towing an underwater device, such as a cutter system for severing marine mine mooring cables, in shallow waters. The system includes a depresser to hold the end of the apparatus nearest the tow vessel at a predetermined depth beneath the surface. A second depressor, or otter, at the outboard end of the apparatus is buoyed upward by the action of a float. The float is completely submerged and contains electronic control circuitry to cause the device to control the outboard end of the towed apparatus at either a predetermined depth, or at a predetermined height above the bottom at the selection of the operator. The position of the float is marked by a surface buoy.

[ Oct. 22, 1974 VARIABLE DEPTH MOORED SWEEP [75] Inventors: Edward .1.Hedbawny, Panama City;

Cecil N. Goff, Maitland; Aubrey G. l-lolston, Panama City, all of Fla.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Aug. 7, 1969 [21] Appl. No.: 851,140

[52] US. Cl. 114/20 B, 114/221 A, 114/235 B [51] Int. Cl... F42b 19/04,B63b 17/00, B63b 35/00 Primary Examiner-Samuel Feinberg AssistantExaminerThomas H. Webb Attorney, Agent, or FirmRichard S. Sciascia; DonD. Doty; William T. Skeer [5 7] ABSTRACT This apparatus, described inthe following specification, comprises an improved system for towing anunderwater device, such as a cutter system for severing marine minemooring cables, in shallow waters. The system includes a depresser tohold the end of the apparatus nearest the tow vessel at a predetermineddepth beneath the surface. A second depressor, or otter, at the outboardend of the apparatus is buoyed upward by the action of a float. Thefloat is completely submerged and contains electronic control circuitryto cause the device to control the outboard end of the towed apparatusat either a predetermined depth, or at a predetermined-height above thebottom at the selection of the operator. The position of the float ismarked by a surface buoy.

10 Claims, 6 Drawing Figures Pmimm 0121221914 842.77 0

sum, 1 tr 4 INVENTORS BY WWI ,13

PATENIEBHBIZZISH Sam M a INVENTORS VARIABLE DEPTH MOORED SWEEP STATEMENTOF GOVERNMENT INTEREST The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

BACKGROUND OF THE INVENTION To effectively sever the mooring cable, thecutting implement should strike the mooring cable a sufficient distancebelow the mine to assure that the cable presents a rigid mechanicalobstruction to the path of the cutting implement. Indeep waters, this isaccomplished by controlling the dept at which theminesweeping gear istowed. That is, if a moored mine is to be effective against ships of anormal draft, it must be moored at a predetermined depth, and the depthat which the minesweeping gear is to be towed is readily determined inrelation to this depth.

Despite the ease at which the optimum towing depth may be determined,the accurate towing of the minesweeping gear at this depth is somewhatdifficult. Should the gear contact the mooring cable near the mine, thelikeihood that the mine will be pulled beneath the mine sweeping gearand the mooring line remain uncut is increased. If the gear is towed toodeep, there is danger that the depressor will ground on the bottom andthe sweep gear will become broken and lost. Because of space limitationson minesweeping craft, a very limited number of spares are carried onboard. Therefore, the loss of major assemblies-due to the aforementionedgrounding frequently requires extensive delays in minesweepingoperations until replacement units are obtained.

The sweeping of mines in inshore areas is particularly troublesome,since the ocean depth varies considerably in such areas. The removal ofmines in these areas is nonetheless important, since the control ofthese waters is essential to establish landing areas and the navalsupport of ground activities. To effectively sweep mines in these areas,it is necessary to repeatedly change the depth at which the minesweepinggear is towed to keep the minesweeping gear at the optimum height toeffect severing the mooring lines without grounding the sweep gear.

To change the depth at which the mine sweeping gear of the prior art istowed, the entire apparatus must be recovered and manual adjustmentsmade thereto. This is a time consuming operation and often results inincomplete sweeps, due either to less than optimum depth of towing ofthe minesweeping gear or to areas not having been traversed by the geardue to navigation inaccuracies encountered during the recovery andrestreaming of the gear.

Prior art systems have attempted to overcome the aforesaid problem byplacing a remote controlled winch within the float at the outboard endof the tow line. The remote controlled winch is then adjusted from thetow vessel to cause the outboard otter to clear the bottom. Such devicesrequire a communication link to transmit command signals. This controllink is subject to detectionand jamming and, often such systems sufferfrom poor response time.

SUMMARY OF THE INVENTION This invention pertains to an improved systemfor sweeping moored marine mines and, more particularly, is directed toa system whereby gear for severing the mooring lines of such mines istowed behind a suitable tractor vehicle. In particular, this inventionpertains to an improved towed minesweeping system wherein the depth ofthe towed minesweeping is regulated to maintain predetermined depth or,selectively, to maintain a predetermined height off the bottom. Further,this invention pertains to a minesweeping system having a positioncontrol for selectively following the bottom a predetermined distancetherefrom including provisions to take the minesweeping gear from thesurface to a minesweeping gear to be towed at a predetermined depth withprovisions to override said control, so as to avoidcollision-with saidbottom. The invention is also, of course, concerned withthe specificelements comprising this system, together with the improved methods ofminesweeping made possible thereby.

Accordingly, it is an object of this invention to provide an improvedminesweeping system.

A further object of this invention is the provision of an improvedminesweeping system effective as a countermeasure against moored mines.

A further object of this invention is the provision of a minesweepingsystem, including a towed marine vehicle with provisions for selectiveregulation of either depth or height off the bottom.

A further object of this invention is the provision of a minesweepingsystem comprising a bottom following vehicle with provisions forautomatic take down of the vehicle when it is on the surface subsequentto be launched.

A further object of this invention is the provision of a minesweepingsystem comprising a towed vehicle having attitude control meanseffective to regulate the depth of said vehicle to a predetermined valueand'having anti-collision control means to prevent the minesweeping gearfrom striking the bottom.

A further object of this invention is the provision of a minesweepingsystem having two selectively actuable control circuits for exercisingprimary control over the minesweeping system, each circuit havingsecondary control functions in the other circuits control system whensaid other circuit is selected as the primary control circuit.

A further object of this invention is the provision of aself-controlled, towed float useful in streaming marinegear atpredetermined depth beneath the surface of-a body of water or at apredetermined height above the bottom thereof.

Other objects and many of the attendant advantages will be readilyappreciated'as the subject invention becomes better understood byreference to the following detailed description,'-when considered inconjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a minesweepingarrangement of the prior art;

FIG. 2 illustrates, in plan view, an offshore minesweeping operation;

FIG. 3 illustrates the system according to the invention;

FIG. 4 illustrates the controlled float which is a component element ofthe system of the invention;

FIG. 5 shows a block diagram of the control circuitry of the inventionwherein the illustrated position of the switches and relays correspondto the bottom following mode of operation with the float on the surface;and

FIG. 6 is a block diagram of the bottom sounding sonar according to theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, where theprior art arrangement is illustrated, a tow vessel 11 is shown towing adepressor 12. A mooring cable cutter 13 is attached to vessel 11 bysuitable tackle carried by depressor 12. At the outboard end of mooringcable cutter 13 is an otter 14, which holds mooring line cutter l3depressed in opposition to the buoying action of float 15 that istransmitted via line 16. Otter 14 also diverts the mooring line cutter13 to one side of the course of tow vessel 11.

When mooring cable cutter 13 contacts a mooring cable 17, one of theindividual cutting elements carried by mooring cable cutter 13 seversthe mooring cable 17 and separates the moored mine 18 from its anchor19. The separated moored mine 18 floats to the surface where it may bedestroyed or disarmed.

As shown in FIGS. 2 and 3, in the minesweeping system of the inventionthe tractor vehicle 21 tows a depressor 22 by a cable 23. A cuttercarrying cable 24 is also towed by tractor vehicle 21 and is heldsubmerged at its forward end by depressor 22. Conventional cuttingimplements sever the mine mooriing cables when they are encountered. Atthe outboard end of the cutter carrying cable 24, an otter 25 divertsthe cable to one side and depresses it against the buoyant action ofcontrolled float 26 attached thereto by a short line 27. A buoy 28,which may be a conventional unit, marks the position of controlled float26 to which it is attached by a suitable light line 29.

FIG. 2 shows, not to scale, the sweeping operation along a coast line31. As will be readily understood, the bottom in such environments hasnaturally occurring irregularities therein. Such irregularities areoccasioned by streams, such as shown at 32, and promontories, such asshown at 33. It is especially important that the cutting implementscarried by line 24 strike the mooring lines at an optimum height abovethe bottom but equally important that they not foul or ground on thebottom.

Tractor vehicle 21 is illustrated as a conventional displacement typemarine vehicle. It should be understood that other types of vehicles maybe employed as tractor vehicles. Particularly suited for suchassignments are rotary wing aircraft and air cushion vehicles, althoughother air and water craft may be used as well.

Likewise, buoy 28 may comprise any suitable lightweight device of thattype which will not produce excessive drag on the towed system. One suchdevice, which is illustrated, is described in U.S. Pat. No.

The particular mooring cutting implements carried by line 24 may also bestate-of-the-art devices. As those versed in minesweeping arts willunderstand, the prior art devices frequently armed explosive actuatedcable cutters. However, good success has been obtained with nonexplosivetypes as well. The latter types offer the advantage of safety ofhandling in addition to the obvious advantage of longer unit life. Onesuch type is disclosed in U.S. Pat. application Ser. No. 775,995 filedby William G. Harris, Jr. on Nov. 8, l968 for Mooring Line CutterSystem.

The heart of the minesweeping system of the invention is a buoyantsubmarine vehicle and the control system therefor. In the minesweepingart such submarine vehicles are termed floats, even though they aretowed submerged. Referring to FIG. 4 where one embodiment of a submarinevehicle which has met with operational success is shown, it is seen thatfloat 26 comprises a body portion 34 and an empennage 35 attachedthereto. I

At the fore and aft ends of body portion 34 are eyes 36. Float 26 issuspended by eyes 36 for storage and maintenance purposes when aboardship or ashore. The relatively small size of eyes 36 contributes to astable mounting for the aforementioned storage and maintenance purposesbut makes streaming and recovery of float 26 thereby difficult. Anenlarged lifting loop 37 is attached to the topside of body portion 34over the center of gravity to facilitate handling float 26 duringstreaming and recovery operations.

At the foreward end of body portion 34 on the topside thereof, anelevated tie point 38 extends upwardly therefrom. Lightweight line 29 isattached to the point 38 so as to connect buoy 28 thereto. If desired, asmall reel or winch may be mounted within the portion of the faring 39protecting the point 38 and line 29 attached thereto. In most instances,however, a fixed length of lightweight line 29 suffices to keep buoy 28within the range necessary to provide marking for the position of float26 and the reel or winch and the control mechanism therefor areunnecessary.

On either side of the foreward portion of body portion 34, fixed wings41 are attached. The primary purpose of wings4l is the provision ofhydrodynamic lift. The lifting force, naturally, supports line 27 withthe attached mooring severing gear. The wings 41 also providedirectional stability to float 26. In this capacity they prevent thefloat from pitching or rolling.

Mounted beneath wings 41 and depending below body portion 34 is a yoke42. Line 27 is attached to yoke 42 and extends therefrom to otter 25, aspreviously noted. Yoke 42 is free to move through a considerable angulararc to accommodate positional variations between float 26 and otter 25.The propulsive force transmitted to float 26 are, of course, impartedthereto via line 27 and yoke 42.

It should be noted that the tackle used in streaming Applicants gear,together with the various lines, splices, connectors, etc., areconventional state-of-the-art designs. For example, lines 23, 24, and 27may be of the self-aligning type illustrated in U.S. Pat. No. 3,368,5l4

issued Feb. 13, 1968, to R. E. Kelly and entitled Symmetrical,Self-Aligning Cable Fairing. Similarly, other state-of-the-art structuremay be used to obtain the specific advantages thereof where suchsubstitutions do not interfere with the overall operation of theinvention and the disclosed cooperation between the individual elementsthereof.

Mounted along the centerline of the float 26 and on the bottom sidethereof, a series of ballast weights 43 provide sufficient mass to theassembly to ensure the desired degree of static buoyancy. Ballastweights 43 are made of lead or other dense material and may, if desired,be located within body portion 34 of float 26. In use, the length ofcutter carrying line 24 and the number and type of cutters attachedthereto may .vary over a wide range. It is therefore more convenient tohave ballast weights 32 located on the external portion of float 26where they may be attached and detached conveniently.

Within the body portion 34 of controlled float 26 is a well 44 for theenclosure of electronic circuit components therein. Well 44 is closedagainst the entry of water by a hatch cover 45. The flow of water acrossthe float 26 as it is towed is enhanced by making'hatch cover 45 shapedto form an uninterrupted surface with the outer surface of body portion34. Hatch cover 45 may, of course, be secured by any conventional meansdeemed appropriate by the skilled artisan making and using the device.Threaded fasteners used with appropriate gasket material have provensatisfactory in use.

Mounted on empennage 35 is an instrument housing 46. A horizontalstabilizer-and controlled elevator assembly 47 are mounted so as toextend outwardly from instrument housing 47 on both sides thereof. Thestabilizer portion of assembly 47, as the name implies, helps controlpitch and roll of float 26. However, it may also contribute to thehydrodynamic lift of float 26 if it is so designed.

As pertains to the instant invention, the controlled elevator functionof assembly 47 is of primary importance. The elevator is controlled toregulate the depth of float 26 as it is towed through the Water. Thiscontrol action is effected in response to certain condition responsiveelectronic circuits to be described herein.

Instrument housing 46 provides a watertight enclosure for suitable drivemotor mechanism, associated control circuitry, and necessarytransmission gearing for moving the elevator surfaces of assembly 47.The motor mechanism is a conventional arrangement. Since a detaileddescription of the motor is unnecessary to the understanding of theinvention, the specific construction thereof is not included herein.Certain electrical aspects of the motor will be described in thediscussion of the electronic circuitry.

An electroacoustic transducer 48 is shown mounted at the foreward end ofinstrument housing 46. The positioning of transducer 48 is a designparameter subject to a considerable degree of choice on the part of thedesign engineer. In general, it should be located toward the aft end ofthe float 26 to prevent shading of its emissions therefrom by yoke 42.However, it may be located other than within instrument housing 46, orother than at the forward end thereof. For example, trans ducer 48 maybe a piezoelectric line array and, in such instances, may be placedalong the bottom of instru-v ment housing 46.

A suitably waterproofed electrical cable 49 connects instrument housing46, and the electronic components contained therein, to the electricaldevices housed within well 44. The exact construction and type of cableemployed for this purpose may be regarded as a matter of design choiceto a person versed in the electronic instrumentation arts.

The present state-of-the-art of electronic circuitry permitstheenclosure of the entire system within instrument housing 46, ifdesired. In such instances, cable 49 is not required. Floats so modifiedhave the advantage of being convertible to and from surface floats 15 ofthe prior art type. Further, float service requirements benefit fromsuch an arrangement since instrument housing 46 and the controlcircuitry contained therein may be stocked, serviced, and shippedseparately from the remaining portions of float 26.

Referring now to FIG. 5, a block diagram representation of the controlcircuitry is shown. A depth selector switch 51 selects a direct currentvoltage to be fed to a level detector 52 in accordance to the positionof a mode switch 53, as will be herein explained. Similarly a bottomheight select switch 54 selects one of a plurality of direct currentvoltages to be fed to level detector in another position of mode switch53.

Level detector 52 compares the voltage supplied it by one of switches 51or 54 with a voltage produced by a corresponding sensor. Depth sensor 55is one of these sensors and it produces a signal corresponding'to thedepth of controlled float 26 beneath the surface of the water. A'varietyof conventional pressure responsive devices may be employed in thiscapacity and, accordingly, no detailed description of such a device isincluded herein. For the purpose of completeness, it is noted that aswitch mechanism actuated by an aneroid pressure sensing mechanism willperform satisfactorily in applicants invention for depth sensor 55.

The other sensor feeding a sensed signal to level detector 52 is bottomsounder 56. Bottom sounder 56 is a height off bottom sonar which will bedescribed in greater detail in conjunction with FIG. 6. It is sufficientfor the purposes of description of FIG. 5 to note that bottom sounder 56provides an electrical signal which is an electrical analog of the rangeto the bottom obtained by echo ranging techniques. Depth sensor 55 alsofeeds an output signal, an electrical analog of the depth beneath thesurface, to a rate detector circuit 57. This signal is fed directlywithout going through mode switch 53. An electrical analog of the timerate of change of the detected depth beneath the surface is produced byrate detector 57 in response to the output of depth sensor 55. Ratedetector 57 may be any suitable conventional time rate of changedetector circuit responsive to signals of both positive and negativepolarity.- Y

The output from rate detector circuit 57, together with the output fromlevel detector 52, is fed to a summing amplifier 58. Summing amplifier58 combines the two input signals into a single output signal ofappropriate magnitude and polarity to be utilized by a motor and drivecircuit 59.

Motor and drive circuit 59 comprise a conventional arrangement of DCmotor, gear transmission, and limit switches to interrupt the operationof the motor at certain predetermined points in the operation thereof.The direction of the rotation of the motor is determined by summingamplifier 58 in accordance with the polarity of the electrical energysupplied the motor thereby. The magnitude of the electrical signalsupplied motor and drive circuit 59 governs the speed of rotation of themotor and, therefore, the speed at which the elevator of assembly 47 ismoved to control the motion of float In addition to supplying an outputsignal to rate detector 57, depth sensor 55 has its output signal fed toa takedown circuit 61. This circuit is a threshhold circuit and producesan output when depth sensor 55 has an output corresponding to apredetermined depth of float 26. This output energizes a relay 62 tocause contacts 62a and 62b to assume their alternate position from thatillustrated in FIG. 5. The purpose of this operation of relay 62, fromwhich the name takedown circuit is derived, will be explained inconjunction with the operation of the device.

Another secondary control circuit, anticollision circuit 63, providessecondary control to prevent depressor-otter or cutter carrying line 24from grounding. Anticollision circuit 63 is shown as comprising abistable switch 73 controlled by two comparator circuits 72 and 74.Comparator 72 is connected so as to have an input from bottom sounder 56and another input from bottom height select switch 54 which serves as astandard to which the input from bottom sounder 56 is compared.Comparator 74 is connected to depth select switch 51 for receipt of astandard signal therefrom and to depth sensor 55 for receipt of a depthanalog signal therefrom. The input of comparator 74 preferably includesa divider network to reduce the depth signals magnitude by apredetermined amount, as will be explained in the description of themode of operation.

The outputs of comparators 72 and 74 are connected to the input ofbistable switch 73. Bistable switch 73 may be any of several known solidstate conduction devices. The conduction state of bistable switch 73 isalternately changed by the outputs of comparators 72 and 74 as will bemore fully explained in connection with the description of the mode ofoperation. In one conduction state bistable switch energizes relay 64 tomove contacts 64a and 64b to their alternate position from thatillustrated in FIG. 5.

When energized, relay 64 changes the connections feeding the inputsignals to level detector 52. The outputs of depth select switch 51 anddepth sensor 55 to level detector 52 are removed and the outputs ofbottom height switch 54 and bottom sounder 56 are substituted therefor.This effectively changes the circuitry to that previously outlined indescribing the bottom following position of mode switch 53.

As noted in the foregoing description of FIG. 5, the individualcircuits, identified by blocks therein, are conventional circuits orhardware with the exception of bottom sounder 56. As disclosed above,bottom sounder 56 is a height of bottom sonar system. This circuitcontinuously echo ranges the bottom and provides an output signal whichis proportional to the height of the float 26 above the bottom.

Referring now to FIG. 6, it is seen that bottom sounder 56 comprises atransmitter 65 which feeds a burst of electrical energy toelectroacoustic transducer 48. The electrical energy is converted byelectroacoustic transducer 48, which may be a piezoelectric device, forexample, to acoustic frequency compressional wave energy. Thecompressional wave energy impinges the bottom and produces an echoreturn therefrom which is returned to transducer 48.

An echo signal is produced by transducer 48 in response to the echoreturn of the compressional wave energy and is fed, via appropriatetransmit receive circuitry, to an amplifier 66. The echo signal isincreased in power level by the action of amplifier 66 and is fed to adetector 67. Detector 67 is a conventional envelope detector andproduces an output having a sharp rise in level corresponding in time ofoccurrence to the receipt of a target return.

The output of detector 67 is differentiated by differentiator 68 towhich it is supplied. Differentiator 68 produces a sharp spike signalcorresponding to the leading edge of echo signal. The differentiatedsignal is fed to a bistable multivibrator 69.

Simultaneously with the feeding a burst of electrical energy totransducer 48, transmitter feeds a synchronizing electrical pulse tobistable multivibrator 69. Upon receipt of this signal, bistablemultivibrator 69 assumes a first conduction state, the flip state. Whenthe spike pulse from differentiator 68 is applied, bistablemultivibrator 69 assumes a second, or flop, conduction state.

As will be readily recognized by those familiar with the electronicarts, the operation of bistable multivibrator 69 is conventional. Thelength of time that bistable multivibrator 69 is in the first, or flip,"conduction state bears a direct, predictable relation to the range ofthe reflecting body returning the compressional wave energy, i.e., thebottom. This time relationship is converted to a voltage analog by theaction of integrator 71 to which the output of bistable multivibrator 69is connected. Integrator 71 produces an output causing float 26 tosurface when bottom sounder 56 receives no bottom return.

From the foregoing description, a person who is skilled in the mooredminesweeping and familar related arts can obtain a complete structuralunderstanding of applicants new and useful combination of elements.Except where noted, the structure and circuitry of the device are ofconventional construction. Accordingly, known equivalent structure may,at the option of the builder, be incorporated herein for performance ofthe equivalent function as will be more fully understood in thefollowing description of the mode of operation.

MODE OF OPERATION The preferred mode of operation of the aforedescribedcomponents comprising the moored minesweeping system of the inventionwill now be described.

Upon entering waters believed to contain moored marine mines, the float26 is made ready to be streamed by suitable crane and other handlinggear on board tractor vehicle 21. Lifting loop 37 facilitates theprelaunch preparation of float 26. While on board tractor vehicle 26,hatch cover 45 is removed, the control circuitry is activated, and thehatch cover 45 secured. Prior to launch buoy 28 is made fast to float 26by securing lightweight line 29 to tie point 38. Cable 27 is next madefast to yoke 42 to suspend otter 25 therebeneath.

Buoy 28, float 26, and otter 25 are lowered away and cable 24, carryingcutters therewith, is payed out. Toward the bitter end of cable 24,depressor 22 is attached by suitable tackle and streamed together withcable 23 attached thereto.

Under the influence of depressor 22 and otter 25, cable 24, includingthe cutters carried thereby, is deplaoyed to the side of tractor vehicle21 and beneath the surface of the water. The depth to which otter 25carries the distal end of cable 24 is regulated by the lifting action offloat 26. In turn, the controlling action of the elevator mechanismportion of assembly 47 determines the amount of lift produced by float26 as it is towed by tractor vessel 21.

Assuming that mode switch 53 is set to the illustrated (FIG. bottomfollowing mode, the control mechanism operates to keep float at aconstant height from the bottom. The position of mode switch 53 obtainedby counterclockwise rotation from the position shown in FIG. 5 producesa depth regulated mode of operation. In the depth regulated mode ofoperation, the control system functions to keep float 26 at a constantdepth beneath the surface of the water.

As previously noted, the illustration of the control circuitry shown inFIG. 5 is shown in the bottom following mode, just subsequent to launch,with controlled float 26 on the surface or just beneath the surface.Under these circumstances, it is diff cult for bottom sounder 56 toacquire the bottom reflection signal. Because of this initial inabilityof bottom sounder 56 to supply a reliable control signal, this initialphase of the bottom following mode of operation is under the control ofdepth select switch 51 and depth sensor 55.

A voltage analog of a predetermined depth of fed level detector 52 viarelay contacts 62a and a first section of mode switch 53. Depth sensor55 produces an electrical signal corresponding to the zero depth offloat 26. This sensed signal is'fed, via relay contacts 62b and a secondsection of mode switch 53, tolevel detector 52.

Level detector 52 compares the two signals and produces a control signalof the proper polarity to drive the motor portion of motor and controlcircuit 59 in a direction to effect an alteration of the angle ofelevator causing float 26 to dive. This signal is amplified by summingamplifier 58 prior to being fed to motorand control circuit 59.

The sensed depth signal from depth sensor 55 is also fed to a ratedetector 57. An electrical signal which is an analog of the time rate ofchange in the vertical direction, i.e., vertical velocity, is producedby rate de tector 57. This rate signal, which is of the oppositepolarity for descent and ascent, 'is fed to summing amplifier 58 whereit provides a partial cancellation, or damping, of the control signalfed by level detector 52. This serves to improve stability of the floatand minimizes violent or abrupt control operations. If left uncorrected,these abrupt changes produce undesirable waves and tensions in the line24.

The sensed depth signal is also fed from depth sensor 55 to take downcircuit 61. When the sensed depth signal exceeds a predetermined value,takedown circuit energizes relay 62, thereby placing contacts 62a and62b in the alternate position from that illustrated.

The value of the detected depth signal necessary to trigger takedowncircuit'6l is predetermined in accordance with the depth at which bottomsounder 56 can acquire the bottom reflection. This may conveniently beadjusted to'correspond to different operating conditions, but it is notordinarily a front panel" control. That is, it need not be adjusted foreach successive use but only when operating conditions changesufficiently height select switch 54 and. bottom sounder 56. The' heightselect switch 54 provides a reference voltage corresponding to theheight off the bottom at which it is desired to position float 26. Thebottom sounder 56, as previously explained, provides level detector 52with a signal voltage analog of the height off the bottom. Leveldetector 52 functions in the same manner as in the case of the depthsignals to produce a control signal to regulate the movement of float 26about this selected height.

It will be observed that the energization of relay 62 has no effect uponthe circuitry of rate detector 57 which continues to receive detecteddepth signals from depth sensor 55. The rate detector 57 together withdepth sensor continues to function as a control during the bottomfollowing mode of operation. This control stabilizes float 26 as tractorvehicle 21 tows it over bottom discontinuities.

This stabilization afforded by the aforediscussed circuitry materiallyassists bottom sounder 56 in maintaining echo ranging contact with thebottom. Should bottom sounder 56 lose contact with the bottom, the failsafe provision of no return signal corresponding to the maximum risesignal causes float 26 to rise to the surface where it may be recovered.

Takedown circuit 61 may be advantageously designed to function as a oneshot device in order to prevent float from porpoising, that isalternately submerging and surfacing, under the combined provisions oftakedown circuit 61- and the failsafe output of bottom sounder 56. Thisprovision may be made internal to the threshholder circuitry, or, ifdesired, may be an electrical or mechanical latching mechanism used inconjunction with relay 62. The interlocking connections may beincorporated. in the power switching mechanism or in the lifting loop37, as will be readily understood by those versed in the arts.

In circumstances where tractor vehicle 21 is to come to a stop fromtime-to-time, the construction of takedown circuit as a one shot deviceis undesirable. Under such stationary conditions of tractor vehicle 21,the small net positive buoyancy of the system causes float 26 tosurface. When tractor vehicle 21 gets underway again, it is desirable tohave takedown circuit 61 functioning to return float 26 to effectivesounding range again. This dual requirement may be incorporated byinterrupting the one shot circuitry, as will be understood by theproficient artisan.

This completes the discussion of the mode of operation of Applicantsinvention in the bottom following mode. From the foregoing discussion,one sees that the float 26 will be operative in this mode to follow thebottom at a predetermined height thereabove. The regulated trajectory offloat 26 keeps cable 24 at the predetermined optimum height in relationto the mooring hardware of marine mines to effect the severing thereof.

To selectively adapt the system to a depth following mode of operation,mode switch 53 is placed in the alternate' position, corresponding tocounterclockwise rotation as seen in FIG. 5. In this position, theoutput of depth select switch 51 and depth sensor 55 are routed to leveldetector 52 via relay contacts 64a and 64b. Depth select switch 51 feedsa voltage analog of a predetermined depth at which it is desired tooperate float 26. The circuit functions as previously explained withlevel detector 52 and rate detector 57 responding to the signals fromthe depth select switch 51 and depth sensor 55 to control the float at apredetermined depth beneath the surface of the water.

When operating in the depth following mode, a danger exists that otter25 or line 24 will ground on a bottom irregularity. To prevent thisundesirable eventuality from occurring, anticollision circuit 63interrupts the depth following control mode when the bottom isapproached within a predetermined distance and changes the control tobottom following. Depth following control is reestablished when float 26attains a depth greater than the set depth by a predetermined amount.

To effect this change of control function, the output 7 from bottomsounder 56 is supplied to comparator 72,

a component part of anticollision circuit 63, where its value iscompared to a reference voltage which, in the preferred embodiment, issupplied by bottom height select switch 54. An output signal isgenerated when the relative magnitude of the two signals corresponds tothe bottom lying at a range less than that selected by the bottom heightselect switch.

The output from comparator 72 is fed to bistable switch 73. Upon thereceipt of the output signal from comparator 72, bistable switch 73changes its conduction state such as to energize relay 64. The relayremains energized until bistable switch 73 receives a signal fromcomparator 74 restoring itto its initial conduction state.

Comparator 74 provides the restoring output when the output of depthsounder 55 exceeds by a predetermined amount the output of depth selectswitch 51, both of these signals comprising the input signals thereto.The establishment of the predetermined amount by which the detecteddepth signal exceeds the selected signal may be accomplished by a simpledivider network, if desired. When bistable switch 73 resumes its initialconduction state, relay 64 is deenergized.

It is energized condition relay 64 moves contacts 64a and 64b to thealternate position than that illustrated in FIG. 5. In this alternateposition, contacts 64a and 64b disconnect depth switch 51 and depthsensor 55 from level detector 52 and connect bottom height select switch54 and bottom sounder 56 therefor. The control circuit functions as abottom follower until the depth obtained by float 26 exceeds the depthset on depth select switch 51 by a predetermined amount, as noted above.

Therefore it is seen that when the primary mode of operation asdetermined by the setting of mode switch 53 is depth following, thebottom sounding circuitry continues to serve as a secondary controlfunction.

It should be understood that the limits of operation of the device areadjustable to meet a variety of operational circumstances and it is inthis light that the term predetermined as it applies to the limits ofoperation is to be understood. For example, to avoid fouling the gear onthe bottom, it is necessary to recognize that cable 24 has a sag whichis dependent on the length thereof and the type of cable severinghardware carried thereby. This sag distance must be taken intoconsideration, as well as the depth required to clear otter 25.Similarly, the overall control system is of the cybernetic type whichhunts about a given control setting the amount of variation is afunction of the sensitivity and response characteristics of thecomponent parts of the system. This response hunt range must be takeninto consideration in the setting of the limits of the point at whichrelay 64 functions to return the control of float 26 to the depthfollowing mode if rapid hunting or relay chatter between the modes is tobe eliminated.

The foregoing description of the preferred embodiment of the inventiontaken together with the'mode of operation thereof and the appendedclaims constitute a complete disclosure of the invention. However, itshould be noted that modification of the details of the device willsuggest themselves to persons proficient in the design and constructionof ocean science instrumentation gear. Examples of such modificationwould be the ganging of switches 51 and 54 to provide a single frontpanel control for both regulation circuits. For extreme lengths ofcutting line, a second controlled float may be employed midwaytherealong. Such modifications are considered to be logical extensionsof the teachings of applicants invention within the normal scope oftechnical expertise of the proficient marine science engineer.

Although Applicants invention has been described in connection with itsuses in marine mine countermeasure systems, it should be clear that thesystem and components thereof have applicability in other arts' whereapparatus must be streamed from marine tow vehicles. UnderwaterSeismology and piscatology, in particular, are arts 'where applicantsinvention may be practiced and utilized to an advantage. Only small,obvious alterations to applicants structure to enable employment inthese arts.

Similarly, it should be apparent that the control system of Applicantscould be utilized in other submarine vehicles where similar control ofthe vehicles running depth is desired. This could include, of course,manned as well as unmanned vehicles.

From the foregoing, it is seen that applicants invention provides aminesweeping system which may be set in accordance with the prevailingconditions to regulate the depth of the cutting system when under tow.The system will function as a bottom following or depth controlledsystem. In either mode of operation the control circuitry of the othermode serves as a secondary control. The system disclosed is seen to meetthe objects of invention, as outlined herein, and to constitute anunobvious, meritorious advance in the marine arts. Further, theinvention provides a significant advance in the marine engineering artswhich is unobvious to a person of ordinary proficiency without thebenefit of the teachings contained herein but, which may be practiced bysuch an artisan having the benefit of these teachings.

What is claimed is:

1. A controlled submarine vehicle adapted for movement within an aqueousmedium having upper and lower boundary surfaces, said vehicle comprisingin combination: a

a body portion;

hydrodynamic lift producing means attached to said body portion in sucha manner as to produce a dynamic force in response to movement throughsaid aqueous medium such as to act on said body portion in a directiongenerally at right angles to the direction of travel thereof for causingmovement between said boundary surfaces;

attitude control means attached to said body portion in such a manner asto alter the angular attitude thereof relative to its direction ofmovement, so as to alter the angle of attack between said hydrodynamiclift producing means and the aqueous medium for altering the dynamiclift produced thereby; and

control circuit means carried within said submarine vehicle andeffectively attached to said attitude control means for movement thereofin response to detected changes of position with respect to a selectedone of said upper and lower boundary surfacesand additionally responsiveto detected positional changes in excess of a predetermined amount withrespect to the nonselected one thereof for self-contained guidance ofsaid controlled submarine vehicle in said aqueous medium.

2. A controlled vehicle according to claim 1 in which said controlcircuit means includes:

pressure responsive means adapted to generate a signal related to thedistance between said controlled vehicle and the upper boundary surfaceof said aqueous medium; r

rate detection means connected to said pressure responsive means forreceipt of said distance related signal therefrom and adapted to producea signal related to the time rate of change thereof; and

summing means effectively connected to said prssure responsive means forreceipt of said distance related signal therefrom and connected to saidrate detection means for receipt of said rate related signal therefromand adapted to generate a control signal in response to said receivedsignals.

3. A controlled vehicle according to claim 1 in which said controlcircuit means includes:

pressure responsive means adapted to generate a signal related to thedistance between said controlled vehicle and the upper boundary surfaceof said aqueous medium;

depth selector means for selecting a signal related to a predetermineddistance from said selected parameter at which it is desired to positionsaid controlled vehicle;

level detector means connected to said pressure responsive means and tosaid depth selector means for receipt of said distance signal and saidselected signal therefrom and adapted to produce a difference signalrelated to the difference in magnitude of said distance signal'and saidselected signal;

rate detection means connected to said pressure responsive means forreceipt of said distance signals therefrom and adapted to produce asignal related to the time rate of change thereof; and

summing means connected to said. level detector means and said ratedetector means for receipt of said difference signal and said time ratesignal therefrom and adapted to generate a control signal in response tosaid received signals.

4. A controlled vehicle according to claim 1 in which said controlcircuit means comprises:

pressure responsive means to generate a first electrical signal relatedto the position of said vehicle with respect to said upper boundarysurface of said aqueous medium;

sounding means to generate a second electrical signal related to theposition of said vehicle with respect to said lower boundary surface ofsaid aqueous medium;

level detector means to generate a control electrical signal in responseto either of said first or second electrical signals;

selector means connected in electrical circuit relationship with saidlevel detector means, said pressure responsive means, and said soundingmeans and being manually adjustable so as to effectively connect saidlevel detector means to either said pressure responsive means or to saidsounding means for receipt of said first and second electrical signalstherefrom;

anticollision means connected to said sounding means for receipt of saidsecond electrical signals therefrom and effectively connected to saidlevel detector means for supplying said second electrical signalsthereto instead of said first electrical signals when said selectormeans in in the position to connect said level detector means to saidpressure responsivemeans and when said second electrical signalcorresponds to the approach of said controlled vehicle within apredetermined distance from said lower boundary surface; and

takedown means connected to said pressure responsive means for receiptof said first electrical signals therefrom and effectively connected tosaid level detector means for supplying said first electrical signalthereto instead of said second electrical signal when said selectormeans is adjusted to connect said level detector means to said soundingmeans for receipt of said second electrical signal therefrom and whensaid controlled vehicle is within a predetermined distance of said upperboundary surface of said aqueous medium.

5. A controlled vehicle according to claim 1 in which said controlcircuit means comprises:

pressure responsive means generating a first detected electrical signalrelated to the position of said vehicle with respect to said upperboundary surface of said aqueous medium; I

depth selector means for selecting a first reference electrical signalrelated to the desired operational distance between said vehicle andsaid upper boundary surface;

sounding means generating a second detected electrical signal related tothe position of said vehicle with respect to said lower boundarysurface;

bottom height selector means for selecting a second reference electricalsignal related to the desired operational distance between said vehicleand said lower boundary surface;

level detector means generating a control electrical signal related tovthe relative magnitudes of detected electrical signals and referenceelectrical signals fed thereto;

mode selector means connected in electrical circuit with said leveldetector means, said pressure responsive means and said depth selectormeans, and said sounding means and said bottom height selector means andbeing manually adjustable to a first position to feed said firstdetected and said first reference signals to said level detector means,or to a second position to feed said second detected and said secondreference signals to said level detector means; and

anticollision means connected to said sounding means and to said bottomheight selector means for receipt of said second detected electricalsignal and said second reference signal therefrom and effectivelyconnected to said level detector means via said mode selector means whenit is in said first position and effective to substitute said second detected and reference signals for said first detected and referencesignals when said vehicle approaches said lower boundary surface withina predetermined distance.

6. A controlled vehicle according to claim 1 in which said controlcircuit means comprises:

pressure responsive means generating a first detected electrical signalrelated to the position of said vehicle with respect to said upperboundary surface of said aqueous medium;

depth selector means for selecting a first reference electrical signalrelated to the desired operational distance between said vehicle andsaid first boundary surface;

sounding means generating a second detected electrical signal related tothe position of said vehicle with respect to said second boundarysurface;

bottom height selector means for selecting a second reference electricalsignal related to the desired operational distance between said vehicleand said lower boundary surface;

level detector means generating a control electrical signal related to,the relative magnitudes of detected electrical signals and referenceelectrical signals fed thereto;

mode selector means connected in electrical circuit with said leveldetector means, said pressure responsive means and said depth selectormeans, and said sounding means and said bottom height selector means andbeing manually adjustable to a first position to feed said firstdetected and said first reference signals to said level detector means,or to a second position to feed said second detected and said secondreference signals to said level detector means;

anticollision means connected to said sounding means and to said bottomheight selector means for receipt of said second detected electricalsignal and said second reference signal therefrom and effectivelyconnected to said level detector means via said mode selector means whenit is in said first position and effective to substitute said seconddetected and reference signals for said first detected and referencesignals when said vehicle approaches said lower boundary surface withina predetermined distance; and

takedown means connected to said pressure responsive means and to saiddepth selector means for receipt of said first detected signal and saidfirst reference signal therefrom and effectively connected to said leveldetector means via said mode selector means when it is in said secondposition and effective to substitute said first detected and referencesignals for said second detected and reference sig- 6 nals when saidvehicle IS within a predetermined distance with respect to said upperboundary surface.

7. A controlled vehicle according to claim 1 in which said controlcircuit means comprises:

pressure responsive means generating a first detected electrical signalrelated to the position of said vehicle with respect to said upperboundary surface of said aqueous medium;

depth selector means for selecting a first reference electrical signalrelated to the desired operational distance between said vehicle andsaid upper boundary surface;

sounding means generating a second detected electrical signal related tothe position of said vehicle with respect to said lower boundarysurface,

bottom height selector means for selecting a second reference electricalsignal related to the desired operational distance between said vehicleand said lower boundary surface;

level detector means generating a control electrical signal related tothe relative magnitudes of detected electrical signals and referenceelectrical signals fed thereto;

mode selector means connected in electrical circuit anticollision meansconnected to said sounding means and to said bottom height selectormeans for receipt of said second detected electrical signal and saidsecond reference signal therefrom and effectively connected to saidlevel detector means via said mode selector means when it is in saidfirst position and effective to substitute said second detected andreference signals for said first detected and reference signals whensaid vehicle approaches said second boundary surface within apredetermined distance, said anticollision means also connected to saidpressure responsiye means and to said depth selector means for receiptof said first detected and reference signals therefrom and effective toterminate the substitution of said second detected and referencesignals, so as to revert to the feeding of said first detected andreference signals to said level detector means, when said vehicleexceeds the depth selected by said depth selector means by apredetermined amount; and

takedown means connected to said pressure respon- 8. A controlledvehicle according to claim 1 in which said control circuit meanscomprises:

pressure responsive means generating a first detected electrical signalrelated to the position of said vehicle with respect to 21 upperboundary surface of said aqueous medium;

depth selector means for selecting a first reference electrical signalrelated to the desired operational distance between said vehicle andsaid upper boundary surface;

sounding means generating a second detected electrical signal related tothe position of said vehicle with respect to said lower boundarysurface;

bottom height selector means for selecting a second reference electricalsignal related to the desired operational distance between said vehicleand said lower boundary surface;

level detector means generating a control electrical signal related tothe relative magnitudes of detected electrical signals and referenceelectrical signals fed thereto;

mode selector means connected in electrical circuit with said leveldetector means, said pressure responsive means and said depth selectormeans, and

said sounding means and said bottom height selector means and beingmanually adjustable to a first position to feed said first detected andsaid first reference signals to said level detector means, or to asecond position to feed said second detected and said second referencesignals to said level detector means;

anticollision means connected to said sounding means and to said bottomheight selector means for receipt of said second detected electricalsignal and said second reference signal therefrom and effectivelyconnected to said level detector means via said mode selector means whenit is in said, first position and effective to substitute said seconddetected and reference signals for said first detected and referencesignals when said vehicle approaches said lower boundary surface withina predetermined distance, said anticollision means also connected tosaid pressure responsive means and to said depth selector means forreceipt of said first detected and reference signals therefrom andeffective to terminate the substitution of said second detected andreference signals; so as to revert to the feeding of said first detectedand reference signals to said level detector means, when said vehicleexceeds the depth selected by said depth selector means by apredetermined amount;

takedown means connected to said pressure responsive means and to saiddepth selector means for receipt of said first detected signal and saidfirst reference signal therefrom and effectively connected to said leveldetector means via said mode selector means when it is in said secondposition and effective to substitute said first detected and referencesignals for said second detected and reference signals when said vehicleis within a predetermined distance with respect to said upper boundarysurface,

rate responsive means connected to said pressure re sponsive means forreceipt of said first detected signal therefrom and producing an outputsignal related to the time rate of change of said first de-' tectedsignal; and summing means connected to said level detector means forreceipt of said control slgnal therefrom and connected to said rateresponsive means for receipt of said rate signal therefrom andgenerating a composite signal related to the sum of said control andrate signals. 9. A controlled vehicle according to claim 1 in which saidcontrol circuit means'comprises:

pressure responsive means generating a first detected electrical signalrelated to the position of said vehicle with respect to said upperboundary surface of said aqueous medium;

depth selector means for selecting a first reference electrical signalrelated to the desired operational distance between said vehicle andsaid upper boundary surface;

sounding means generating a second detected electrical signal related tothe position of said vehicle with respect to said lower boundarysurface;

bottom height selector means for selecting a second reference electricalsignal related to the desired operational distance between said vehicleand said lower boundary surface;

level detector means generating a control electrical signal related tothe relative magnitudes of detected electrical signals and referenceelectrical signals fed thereto;

mode selector means connected in electrical circuit with said leveldetector means, said pressure responsive means and said depthselectormeans, and said sounding means and said bottom height selec- 'tor meansand being manually adjustable to a first position to feed said firstdetected and said first reference signals to said level detector means,or to a second position to feed said second detected and said secondreference signals to said level detector means; 7

anticollision means connected to said sounding means and to said bottomheight selector means for receipt of said second detected electricalsignal and said second reference signal therefrom and effectivelyconnected to said level detector means via said mode selector means whenit is in said first position and'effective to substitute said seconddetected and reference signals for said first detected and referencesignals when said vehicle approaches said lower boundary surface withina predetermined distance, said anticollision means also connected tosaid' pressure responsive means and to said depth selector means forreceipt of said first detected and reference signals therefrom andeffective to terminate the substitution of said second detected andreference signals, so as to revert to the feeding of said first detectedand reference signals to said level detector means, when said vehicleexceeds the depth selected'by said depth selector means by apredetermined amount;

takedown means connected to said pressure responsive means and to saiddepth selector means for receipt of said first detected signal and saidfirst reference signal therefrom and effectively connected to said leveldetector means via said mode selector means when it is in said secondposition and effective to substitute said first detected and referencesignals for said second detected and reference signals when said vehicleis within a predetermined distance with respect to said upper boundarysurface;

rate responsive means connected to said pressure responsive means forreceipt of said first detected signal therefrom and producing an outputsignal related to the time rate of change of said first detected signal;

summing means connected to said level detector means for receipt of saidcontrol signals therefrom and connected to said rate responsive meansfor receipt of said rate signals therefrom and generating a compositesignal related to the sum of said control and rate signals; and

motor means electrically connected to said summing means for receipt ofsaid composite signal therefrom and operative so as to be electricallydriven thereby and connected mechanically to said attitude controlmeans.

10. A countermeasure system for concealed explosive means which areattached to mooring lines so as to be moored within an aqueous mediumhaving an upper and lower boundary surface, said system comprising:

tractor vehicle means operating proximate to said upper boundary of saidaqueous medium and providing propulsive force for said system;

tow line means attached at its bitter end to said tractor vehicle means;depressor means attached to said tow line means at the distal endthereof for providing a dynamic force as a result of the propulsiveforce imparted thereto by said tractor vehicle via said towline means toeffect the submergence within the aqueous medium of said distal endthereof; cutter line means attached to said tractor vehicle at thebitter end thereof and attached to said depressor means at anintermediate point therealong to extend beyond said depressor means;

cutting means attached to said cutter line at intervals along saidportion thereof extending beyond said depressor means;

otter-depressor means attached to said cutter line at the distal endthereof and responsive to the propulsive force transmitted thereto bysaid cutter line to 20 deploy said cutter line in a laterally protrusilerelationship to the course of said tractor vehicle and submerged withinsaid aqueous medium; and

float vehicle means attached to said otter-depressor means for buoyingsaid otter-depressor and the cutter line carried thereby to a controlledposition within said aqueous medium predetermined as an optimumintercept point of said mooring lines, said float vehicle meanscomprising;

a body portion;

hydrodynamic lift producing means attached to said body portion forproducing a dynamic force as said float is towed through said aqueousmedium to oppose the depressing action of said otter-depressor means;

attitude control means effectively attached to said body portion forchanging the angular attitude thereof relative to the direction oftowing movement thereof so as to effectively alter the angle betweensaid lift producing means and the direction of relative flow of theaqueous medium;

pressure responsive means responsive to the pressure of the aqueousmedium at the float level to generate a signal related to the distancebetween said float and said upper boundary surface;

sounding means generating a signal related to the distance between saidfloat and said lower boundary surface; and 7 control circuit meanswithin said body portion and connecting said pressure responsive meansand said sounding means to said attitude control means for selectiveoperation thereof by a selected one of the signal outputs of saidpressure responsive means or said sounding means. addition, the heatoutput per unit of combusted gas is very good.

1. A controlled submarine vehicle adapted for movement within an aqueousmedium having upper and lower boundary surfaces, said vehicle comprisingin combination: a body portion; hydrodynamic lift producing meansattached to said body portion in such a manner as to produce a dynamicforce in response to movement through said aqueous medium such as to acton said body portion in a direction generally at right angles to thedirection of travel thereof for causing movement between said boundarysurfaces; attitude control means attached to said body portion in such amanner as to alter the angular attitude thereof relative to itsdirection of movement, so as to alter the angle of attack between saidhydrodynamic lift producing means and the aqueous medium for alteringthe dynamic lift produced thereby; an control circuit means carriedwithin said submarine vehicle and effectively attached to said attitudecontrol means for movement thereof in response to detected changes ofposition with respect to a selected one of said upper and lower boundarysurfaces and additionally responsive to detected positional changes inexcess of a predetermined amount with respect to the nonselected onethereof for self-contained guidance of said controlled submarine vehiclein said aqueous medium.
 2. A controlled vehicle according to claim 1 inwhich said control circuit means includes: pressure responsive meansadapted to generate a signal related to the distance between saidcontrolled vehicle and the upper boundary surface of said aqueousmedium; rate detection means connected to said pressure responsive meansfor receipt of said distance related signal therefrom and adapted toproduce a signal related to the time rate of change thereof; and summingmeans effectively connected to said prssure responsive means for receiptof said distance related signal therefrom and connected to said ratedetection means for receipt of said rate related signal therefrom andadapted to generate a control signal in response to said receivedsignals.
 3. A controlled vehicle according to claim 1 in which saidcontrol circuit means includes: pressure responsive means adapted togenerate a signal related to the distance between said controlledvehicle and the upper boundary surface of said aqueous medium; depthselector means for selecting a signal related to a predetermineddistance from said selected parameter at which it is desired to positionsaid controlled vehicle; level detector means connected to said pressureresponsive means and to said depth selector means for receipt of saiddistance signal and said selected signal therefrom and adapted toproduce a difference signal related to the difference in magnitude ofsaid distance signal and said selected signal; rate detection meansconnected to said pressure responsive means for receipt of said distancesignals therefrom and adapted to produce a signal related to the timerate of change thereof; and summing means connected to said leveldetector means and said rate detector means for receipt of saiddifference signal and said time rate signal therefrom and adapted togenerate a control signal in response to said received signals.
 4. Acontrolled vehicle according to claim 1 in which said control circuitmeans comprises: pressure responsive means to generate a firstelectrical signal related to the position of said vehicle with respectto said upper boundary surface of said aqueous medium; sounding means togenerate a second electrical signal related to the position of saidvehicle with respect to said lower boundary surface of said aqueousmedium; level detector means to generate a control electrical signal inresponse to either of said first or second electrical signals; selectormeans connected in electrical circuit relationship with said leveldetector means, said pressure responsive means, and said sounding meansand being manually adjustable so as to effectively connect said leveldetector means to either said pressure responsive means or to saidsounding means for receipt of said first and second electrical signalstherefrom; anticollision means connected to said sounding means forreceipt of said second electrical signals therefrom and effectivelyconnected to said level detector means for supplying said secondelectrical signals thereto instead of said first electrical signals whensaid selector means in in the position to connect said level detectormeans to said pressure responsive means and when said second electricalsignal corresponds to the approach of said controlled vehicle within apredetermined distance from said lower boundary surface; and takedownmeans connected to said pressure responsive means for receipt of saidfirst electrical signals therefrom and effectively connected to saidlevel detector means for supplying said first electrical signal theretoinstead of said second electrical signal when said selector means isadjusted to connect said level detector means to said sounding means forreceipt of said second electrical signal therefrom and when saidcontrolled vehicle is within a predetermined distance of said upperboundary surface of said aqueous medium.
 5. A controlled vehicleaccording to claim 1 in which said control circuit means comprises:pressure responsive means generating a first detected electrical signalrelated to the position of said vehicle with respect to said upperboundary surface of said aqueous medium; depth selector means forselecting a first reference electrical signal related to the desiredoperational distance between said vehicle and said upper boundarysurface; sounding means generating a second detected electrical signalrelated to the position of said vehicle with respect to said lowerboundary surface; bottom height selector means for selecting a secondreference electrical signal related to the desired operational distancebetween said vehicle and said lowEr boundary surface; level detectormeans generating a control electrical signal related to the relativemagnitudes of detected electrical signals and reference electricalsignals fed thereto; mode selector means connected in electrical circuitwith said level detector means, said pressure responsive means and saiddepth selector means, and said sounding means and said bottom heightselector means and being manually adjustable to a first position to feedsaid first detected and said first reference signals to said leveldetector means, or to a second position to feed said second detected andsaid second reference signals to said level detector means; andanticollision means connected to said sounding means and to said bottomheight selector means for receipt of said second detected electricalsignal and said second reference signal therefrom and effectivelyconnected to said level detector means via said mode selector means whenit is in said first position and effective to substitute said seconddetected and reference signals for said first detected and referencesignals when said vehicle approaches said lower boundary surface withina predetermined distance.
 6. A controlled vehicle according to claim 1in which said control circuit means comprises: pressure responsive meansgenerating a first detected electrical signal related to the position ofsaid vehicle with respect to said upper boundary surface of said aqueousmedium; depth selector means for selecting a first reference electricalsignal related to the desired operational distance between said vehicleand said first boundary surface; sounding means generating a seconddetected electrical signal related to the position of said vehicle withrespect to said second boundary surface; bottom height selector meansfor selecting a second reference electrical signal related to thedesired operational distance between said vehicle and said lowerboundary surface; level detector means generating a control electricalsignal related to the relative magnitudes of detected electrical signalsand reference electrical signals fed thereto; mode selector meansconnected in electrical circuit with said level detector means, saidpressure responsive means and said depth selector means, and saidsounding means and said bottom height selector means and being manuallyadjustable to a first position to feed said first detected and saidfirst reference signals to said level detector means, or to a secondposition to feed said second detected and said second reference signalsto said level detector means; anticollision means connected to saidsounding means and to said bottom height selector means for receipt ofsaid second detected electrical signal and said second reference signaltherefrom and effectively connected to said level detector means viasaid mode selector means when it is in said first position and effectiveto substitute said second detected and reference signals for said firstdetected and reference signals when said vehicle approaches said lowerboundary surface within a predetermined distance; and takedown meansconnected to said pressure responsive means and to said depth selectormeans for receipt of said first detected signal and said first referencesignal therefrom and effectively connected to said level detector meansvia said mode selector means when it is in said second position andeffective to substitute said first detected and reference signals forsaid second detected and reference signals when said vehicle is within apredetermined distance with respect to said upper boundary surface.
 7. Acontrolled vehicle according to claim 1 in which said control circuitmeans comprises: pressure responsive means generating a first detectedelectrical signal related to the position of said vehicle with respectto said upper boundary surface of said aqueous medium; depth selectormeans for selecting a first reference electrical signal related to thedesireD operational distance between said vehicle and said upperboundary surface; sounding means generating a second detected electricalsignal related to the position of said vehicle with respect to saidlower boundary surface, bottom height selector means for selecting asecond reference electrical signal related to the desired operationaldistance between said vehicle and said lower boundary surface; leveldetector means generating a control electrical signal related to therelative magnitudes of detected electrical signals and referenceelectrical signals fed thereto; mode selector means connected inelectrical circuit with said level detector means, said pressureresponsive means and said depth selector means, and said sounding meansand said bottom height selector means and being manually adjustable to afirst position to feed said first detected and said first referencesignals to said level detector means, or to a second position to feedsaid second detected and said second reference signals to said leveldetector means; anticollision means connected to said sounding means andto said bottom height selector means for receipt of said second detectedelectrical signal and said second reference signal therefrom andeffectively connected to said level detector means via said modeselector means when it is in said first position and effective tosubstitute said second detected and reference signals for said firstdetected and reference signals when said vehicle approaches said secondboundary surface within a predetermined distance, said anticollisionmeans also connected to said pressure responsive means and to said depthselector means for receipt of said first detected and reference signalstherefrom and effective to terminate the substitution of said seconddetected and reference signals, so as to revert to the feeding of saidfirst detected and reference signals to said level detector means, whensaid vehicle exceeds the depth selected by said depth selector means bya predetermined amount; and takedown means connected to said pressureresponsive means and to said depth selector means for receipt of saidfirst detected signal and said first reference signal therefrom andeffectively connected to said level detector means via said modeselector means when it is in said second position and effective tosubstitute said first detected and reference signals for said seconddetected and reference signals when said vehicle is within apredetermined distance with respect to said first boundary surface.
 8. Acontrolled vehicle according to claim 1 in which said control circuitmeans comprises: pressure responsive means generating a first detectedelectrical signal related to the position of said vehicle with respectto a upper boundary surface of said aqueous medium; depth selector meansfor selecting a first reference electrical signal related to the desiredoperational distance between said vehicle and said upper boundarysurface; sounding means generating a second detected electrical signalrelated to the position of said vehicle with respect to said lowerboundary surface; bottom height selector means for selecting a secondreference electrical signal related to the desired operational distancebetween said vehicle and said lower boundary surface; level detectormeans generating a control electrical signal related to the relativemagnitudes of detected electrical signals and reference electricalsignals fed thereto; mode selector means connected in electrical circuitwith said level detector means, said pressure responsive means and saiddepth selector means, and said sounding means and said bottom heightselector means and being manually adjustable to a first position to feedsaid first detected and said first reference signals to said leveldetector means, or to a second position to feed said second detected andsaid second reference signals to said level detector means;anticollision means connected to said sounding means and to said bottomheight selector means for receipt of said second detected electricalsignal and said second reference signal therefrom and effectivelyconnected to said level detector means via said mode selector means whenit is in said first position and effective to substitute said seconddetected and reference signals for said first detected and referencesignals when said vehicle approaches said lower boundary surface withina predetermined distance, said anticollision means also connected tosaid pressure responsive means and to said depth selector means forreceipt of said first detected and reference signals therefrom andeffective to terminate the substitution of said second detected andreference signals, so as to revert to the feeding of said first detectedand reference signals to said level detector means, when said vehicleexceeds the depth selected by said depth selector means by apredetermined amount; takedown means connected to said pressureresponsive means and to said depth selector means for receipt of saidfirst detected signal and said first reference signal therefrom andeffectively connected to said level detector means via said modeselector means when it is in said second position and effective tosubstitute said first detected and reference signals for said seconddetected and reference signals when said vehicle is within apredetermined distance with respect to said upper boundary surface, rateresponsive means connected to said pressure responsive means for receiptof said first detected signal therefrom and producing an output signalrelated to the time rate of change of said first detected signal; andsumming means connected to said level detector means for receipt of saidcontrol signal therefrom and connected to said rate responsive means forreceipt of said rate signal therefrom and generating a composite signalrelated to the sum of said control and rate signals.
 9. A controlledvehicle according to claim 1 in which said control circuit meanscomprises: pressure responsive means generating a first detectedelectrical signal related to the position of said vehicle with respectto said upper boundary surface of said aqueous medium; depth selectormeans for selecting a first reference electrical signal related to thedesired operational distance between said vehicle and said upperboundary surface; sounding means generating a second detected electricalsignal related to the position of said vehicle with respect to saidlower boundary surface; bottom height selector means for selecting asecond reference electrical signal related to the desired operationaldistance between said vehicle and said lower boundary surface; leveldetector means generating a control electrical signal related to therelative magnitudes of detected electrical signals and referenceelectrical signals fed thereto; mode selector means connected inelectrical circuit with said level detector means, said pressureresponsive means and said depth selector means, and said sounding meansand said bottom height selector means and being manually adjustable to afirst position to feed said first detected and said first referencesignals to said level detector means, or to a second position to feedsaid second detected and said second reference signals to said leveldetector means; anticollision means connected to said sounding means andto said bottom height selector means for receipt of said second detectedelectrical signal and said second reference signal therefrom andeffectively connected to said level detector means via said modeselector means when it is in said first position and effective tosubstitute said second detected and reference signals for said firstdetected and reference signals when said vehicle approaches said lowerboundary surface within a predetermined distance, said anticollisionmeans also connected to said pressure responsive means and to said depthselector means for receipt of saiD first detected and reference signalstherefrom and effective to terminate the substitution of said seconddetected and reference signals, so as to revert to the feeding of saidfirst detected and reference signals to said level detector means, whensaid vehicle exceeds the depth selected by said depth selector means bya predetermined amount; takedown means connected to said pressureresponsive means and to said depth selector means for receipt of saidfirst detected signal and said first reference signal therefrom andeffectively connected to said level detector means via said modeselector means when it is in said second position and effective tosubstitute said first detected and reference signals for said seconddetected and reference signals when said vehicle is within apredetermined distance with respect to said upper boundary surface; rateresponsive means connected to said pressure responsive means for receiptof said first detected signal therefrom and producing an output signalrelated to the time rate of change of said first detected signal;summing means connected to said level detector means for receipt of saidcontrol signals therefrom and connected to said rate responsive meansfor receipt of said rate signals therefrom and generating a compositesignal related to the sum of said control and rate signals; and motormeans electrically connected to said summing means for receipt of saidcomposite signal therefrom and operative so as to be electrically driventhereby and connected mechanically to said attitude control means.
 10. Acountermeasure system for concealed explosive means which are attachedto mooring lines so as to be moored within an aqueous medium having anupper and lower boundary surface, said system comprising: tractorvehicle means operating proximate to said upper boundary of said aqueousmedium and providing propulsive force for said system; tow line meansattached at its bitter end to said tractor vehicle means; depressormeans attached to said tow line means at the distal end thereof forproviding a dynamic force as a result of the propulsive force impartedthereto by said tractor vehicle via said towline means to effect thesubmergence within the aqueous medium of said distal end thereof; cutterline means attached to said tractor vehicle at the bitter end thereofand attached to said depressor means at an intermediate point therealongto extend beyond said depressor means; cutting means attached to saidcutter line at intervals along said portion thereof extending beyondsaid depressor means; otter-depressor means attached to said cutter lineat the distal end thereof and responsive to the propulsive forcetransmitted thereto by said cutter line to deploy said cutter line in alaterally protrusile relationship to the course of said tractor vehicleand submerged within said aqueous medium; and float vehicle meansattached to said otter-depressor means for buoying said otter-depressorand the cutter line carried thereby to a controlled position within saidaqueous medium predetermined as an optimum intercept point of saidmooring lines, said float vehicle means comprising; a body portion;hydrodynamic lift producing means attached to said body portion forproducing a dynamic force as said float is towed through said aqueousmedium to oppose the depressing action of said otter-depressor means;attitude control means effectively attached to said body portion forchanging the angular attitude thereof relative to the direction oftowing movement thereof so as to effectively alter the angle betweensaid lift producing means and the direction of relative flow of theaqueous medium; pressure responsive means responsive to the pressure ofthe aqueous medium at the float level to generate a signal related tothe distance between said float and said upper boundary surface;sounding means generating a signal related to the distance between saidfloat and said lower bouNdary surface; and control circuit means withinsaid body portion and connecting said pressure responsive means and saidsounding means to said attitude control means for selective operationthereof by a selected one of the signal outputs of said pressureresponsive means or said sounding means. addition, the heat output perunit of combusted gas is very good.